/bjc

REVIEWARTICLEMetastasis

Mutationaldriversofcancercellmigrationandinvasion

NikitaM.Novikov1,So?aY.Zolotaryova1,AlexisM.Gautreau2,3andEvgenyV.Denisov1

Genomicinstabilityandmutationsunderliethehallmarksofcancer—geneticalterationsdeterminecancercellfatebyaffectingcellproliferation,apoptosisandimmuneresponse,andincreasingdatashowthatmutationsareinvolvedinmetastasis,acrucialeventincancerprogressionandalife-threateningproblemincancerpatients.Invasionisthe?rststepinthemetastaticcascade,whentumourcellsacquiretheabilitytomove,penetrateintothesurroundingtissueandenterlymphaticandbloodvesselsinordertodisseminate.Aroleforgeneticalterationsininvasionisnotuniversallyaccepted,withscepticsarguingthatcellularmotilityis

relatedonlytoexternalfactorssuchashypoxia,chemoattractantsandtherigidityoftheextracellularmatrix.However,increasingevidenceshowsthatmutationsmighttriggerandacceleratethemigrationandinvasionofdifferenttypesofcancercells.Inthisreview,wesummarisedatafrompublishedliteratureontheeffectofchromosomalinstabilityandgeneticmutationsoncancercellmigrationandinvasion.

BritishJournalofCancer(2021)124:102–114;

/10.1038/s41416-020-01149-0

BACKGROUND

Geneticabnormalitieslieattheheartofmostcancers—mutations

cantransformnormalcellsintocancerousonesbyendowing

themwithnewproperties.Genomeinstabilityandmutations

determinethehallmarksofcancer,oneofwhichistheabilityof

tumourcellstoinvadeandmetastasise.

1

Metastasisistheleading

causeofdeathfromcancer.Duringtheprocessofmetastasis,

tumourcellsleavetheprimarysiteandspreadthroughoutthe

body,formingsecondarysitesandcausingsevereorganfailure.

2

The?rststepofthemetastaticcascadeisinvasion,inwhich

tumourcellspenetratetheirsurroundingbasementmembrane

andmigratethroughtheextracellularmatrix(ECM)intothe

surroundingtissue(Fig.

1

).

3

Severaldifferentparametersinthetumourmicroenvironment

inluencetheregulationofcancercellmigrationandinvasion:the

presenceofhypoxia,chemoattractants,ECMstiffnessandalackof

nutrientspromptcancercellstostartsearchingfora‘betterlife’.

4

Ofparticularsigni?canceduringmigrationandinvasionisthe

phenomenonofepithelial-to-mesenchymaltransition(EMT),

whichdeterminestheplasticityoftumourcells,allowingthem

toswitchfromanon-motileepithelialtoamotilemesenchymal

state,andendowingcancercellswithmultiplemalignantfeatures,

suchastheincreasedinvasivenessandresistancetosenescence,

apoptosisandtreatment.

2

TheEMTisactivatedbytranscription

factors,suchasTwist,Snail,SlugandZeb1,throughvarious

signallingpathways,themostimportantbeingTGF-β,WNTand

Notchpathways.

5

Theavailabilityofthesetranscriptionfactorscan

thereforeofferameansofregulatingthisreversibleandplastic

translationallevels.

5

Theimpactofsomaticmutationsincurred

process,withcontrolalsooccurringatepigeneticandpost-

duringprimarytumourformationonEMTremainstobe

elucidated.

2

Theroleofgeneticalterationsintumourcellmigrationand

invasionhasreceivedundeservedlylittleattentioncomparedwith

epigeneticandtranscriptionalmechanismsofcellmotility.Despite

thehugeamountofexperimentaldataregardingtheeffectof

mostofwhichfocusmainlyonthetumoursuppressorp53.

6

,

7

In

geneticmutationsoncancerinvasion,onlyafewreviewsexist,

thisreview,wesummarisepublisheddataoutliningchromosomal

instability(CIN)andgenealterationsthatimpingeonsomeofthe

molecularcomponentsthatarecrucialforcancercellmigration

andinvasion.Wealsodiscussthemaindif?cultiesencounteredin

identifyinggeneticalterationsthatdrivecancerinvasionand

suggestpotentialmodelsandapproachestoovercomethese

problems.Finally,weunderscorethesigni?canceofidentifying

mutationaldriversofcancerinvasionaspotentialtherapeutic

targetsforthepreventionofmetastaticdisease.

CHROMOSOMALINSTABILITY

CIN,whichincludeschangesinthenumberofchromosomesas

wellastheirrearrangement,isobservedinmanytumourtypes

andisassociatedwithtumourprogression,asdescribedinBox1.

8

Forexample,asshowninMDA-MB-231triple-negativebreast

cancercellsinvitroandinvivo,CINcaninducethetranscriptional

transitionoftumourcellstoamesenchymalstatecharacterisedby

increasedmigratoryandinvasivebehaviourwiththeactivationof

inlammatorypathways.

9

Byincreasinginlammation,CINcanalso

promotecancermetastasis.

9

,

10

Itisworthnoting,however,that

CINcaninluencetheinvasiveandmetastaticpotentialdifferently,

1LaboratoryofCancerProgressionBiology,CancerResearchInstitute,TomskNationalResearchMedicalCenter,RussianAcademyofSciences,Tomsk,Russia;2CNRSUMR7654,EcolePolytechnique,InstitutPolytechniquedeParis,Palaiseau,Franceand3SchoolofBiologicalandMedicalPhysics,MoscowInstituteofPhysicsandTechnology,Dolgoprudny,Russia

Correspondence:EvgenyV.Denisov(

d_evgeniy@oncology.tomsk.ru

)

Received:2April2020Revised:13October2020Accepted:15October2020

Publishedonline:18November2020

?TheAuthor(s),underexclusivelicencetoCancerResearchUK2020

Tumourcells

BasementmembraneExtracellularmatrix

EndothelialcellsBloodvessel

Fig.1Themodelofcancercellinvasion.Cancerinvasionisthe?rststepofthemetastaticcascade.Tumourcellspenetratethebasementmembraneandinvadethesurroundingtissuesusingtwomodesofmovement—individualandcollectiveinvasion.Invadingtumourcellsreachthebloodvessel,entertheblood?owanddisseminate,eventuallygivingrisetosecondarytumours.

Box1AbriefoverviewoftheprocessesresponsibleforCIN

CIN,oneoftheformsofgenomicinstabilityintumours,ischaracterisedbyan

increaseintherateoflossorgainofwholechromosomesortheirfragments

duringcelldivision.CINhasasevereandcompleximpactonthegenetic

landscapeofthetumourbyaffectingvariousoncogenes,tumour-suppressor

genesandDNA-repairgenesthatdrivecancergrowthandprogression.CIN

promotesintratumouralheterogeneityandclonalevolution,givingcancercells

anadvantageunderselectivepressure.

8

DifferentmitoticeventsunderlieCIN.Amongthemarecohesiondefects,

dysfunctioninspindleassemblycheckpoint,centrosomeampli?cationand

cytokinesisfailure.DefectsinDNAreplicationandrepair,suchastelomere

dysfunctionandreplicationstress,arealsoresponsibleforCIN.Allthesechanges

leadtochromosomemissegregationduringmitosisandpavethewayto

polyploidy,aneuploidyanddiversechromosomalrearrangements.

212

,

213

TheroleofCINincancergrowthandprogressionremainsdebatable.Some

researchersconsiderCINtobeanearlyeventincancer,andsomebelievethat

CINissimplyasideeffectoftumourgrowth.

8

Inanyevent,CINissigni?cantly

associatedwithdrugresistanceandcancerprogression.

8

,

10

microenvironment(reviewedinref.

10

).

dependingonthemolecularlandscapeoftumourcellsandtheir

TwotypesofCINcanbedistinguished(Fig.

2

):numericalCIN,

whichisdeterminedbythegainorlossofwholechromosomes

(aneuploidy)andchromosomesets(polyploidy),andstructural

CIN,whichinvolvesfractionsofchromosomesandcanresultin

genefusions,ampli?cationsandotheralterations.

8

Inbothcases,

lossofheterozygosity(LOH)—de?nedasthelossofoneallele

causedbydeletion,mitoticrecombination,geneconversionor

lossofachromosome—canarise.

11

LOHisacommonalterationin

cancer;itresultsinhaploinsuf?ciencyorlossofgeneexpression,

andfrequentlyaffectstumour-suppressorgenes,therebycon-

tributingtotumorigenesis.Inaddition,LOH—aloneortogether

withothergeneticorepigeneticalterations—caninluencethe

abilityofcancercellstoinvade.

12

,

13

Forexample,LOHofthe8p22

chromosomalregion(DLC1,whichencodesaRhoGTPase-

activatingprotein)promotesmigrationandinvasionofbreast,

14

lung,

15

prostate

16

andliver

17

cancercellsinvitro.

18

LOHofthe8p

MutationaldriversofcancercellmigrationandinvasionNMNovikovetal.

103

NumericalCIN

Polyploidy

PGCCanddaughtercells

Genefusion

Cancerinvasion

Amplification

BCR-ABL,TMPRSS2-ERG,

etc.

Amplificationofgenesandchromosomalregions(ErbB2,EGFR,11q13,etc.)

StructuralCIN

Lossof

heterozygosity

Monosomyandtrisomy

LOHof1p32,8p,etc.

Aneuploidy

Fig.2Chromosomalinstabilityandcancerinvasion.Chromoso-malinstability(CIN)isoneofthecancerhallmarksandplaysanimportantroleintumourcellmigrationandinvasion.CINcanberepresentedbygainorlossofwholechromosomes(numericalCIN)andchromosomalrearrangements(structuralCIN).Lossofhetero-zygosity(LOH)thatcanbeattributedtonumericalandstructuralCINsimultaneously,dependingonthetypeofgenomicchangesresultinginthealleleloss,affectstheinvasivepotentialoftumourcells.Polyploidyde?nedasthepresenceofadditionalsetsofchromosomesdrasticallychangesthegeneticlandscapeoftumourcells,endowingthemwithhighinvasivepotential.Polyploidgiantcancercells(PGCCs)arefoundinvariouscancersandshowextremetumorigenic,invasiveandmetastaticpotential.Aneuploidywhenchromosomescanbelost(monosomy)orgained(trisomy)canhavedifferenteffectsontumourcellinvasion:fromattenuationofmigratorybehaviourtoitsenhancement.Differentgenefusionsarisingfromvariouschromosomalrearrangementsaffecttumourcellmotilitythroughdiversesignallingpathwaysandmechanisms.Ampli?cationde?nedasacopynumberincreaseofacertainregionofthegenomeleadstoenhancedgeneexpressionand,ifagenepositivelyregulatescellularmotility,itcanacceleratecancerinvasion.

regionleadstochangesinlipidmetabolism,which,inturn,

increasesthemotilityandinvasivenessofMCF10Abreastcells

invitro.

19

LossoftheexpressionofTGFBR3,whichencodesTGF-

βR3,duetoLOHofthe1p32region,enhancesmigrationand

invasionofA549non-small-celllungcancer(NSCLC)cells

invitro.

20

NumericalCIN

Gainorlossofwholechromosomes(aneuploidy)orchromosome

sets(polyploidy)arefrequenteventsinvariouscancersandcan

drasticallyaffecttumourprogressionnotonlythroughtranscrip-

tomicchangesbutalsothroughtheenhancementofCINitself,

creatingmoreandmoregeneticallydistinctcancercellclones.

8

Itisbelievedthatthepolyploidisationoftumourcellsisonlya

steponthepathtoaneuploidy.

21

,

22

However,polyploidtumour

cellscanexistwithouttransitioningtoaneuploidy.

21

Polyploidtumourcellscontributesigni?cantlytocancer

progression.Polyploidgiantcancercells(PGCCs)areformedby

endoreplicationorfusionofseveralcells,andarefoundinhigh-

gradeandchemoresistantcancers,predominantlyinbreast,

ovarianandcolorectalcancers.

23

,

24

PGCCscansurviveanticancer

Mutationaldriversofcancercellmigrationandinvasion

NMNovikovetal.

104

therapy,areextremelytumorigenicandcontributetocancer

metastasis.

23

,

24

PGCCsandtheirdaughtercells,collectivelycalled

tumourbudsandlocatedattheinvasivefrontoftumours,

25

have

amesenchymalphenotypeandahighcapacityforinvasion

throughchangesintheexpressionoffactorsthatmediateEMT.

26

-

28

IntheMDA-MB-231breastcancercellline,PGCCsmovedmore

slowlythannormalcancercells,butshowedhighmigratory

persistence.

29

Thismigratoryphenotypeisassociatedwiththe

dysregulationoftheactinnetworkandRhoA-Rho-associated

proteinkinase(ROCK)1signallingpathway,whichdrivesincreased

cellstiffness.

29

AsshowninLoVoandHCT116colorectalcancercells

invitroandinvivo,themigrationandinvasionofPGCCsandtheir

daughtercellsmightbedeterminedbyS100A4anditsassociated

molecularnetwork,potentiallyinvolvingregulationofthestructure

andfunctionoftheannexinA2-S100A10complextoinluence

cathepsinB,aswellascytoskeletalassociationswith14-3-3ζ/δand

ezrin.

30

InadditiontoPGCCs,otherpolyploidcellscancontributeto

tumourmetastasis.Forexample,asshownintheDLD-1cellline,

tetraploidtumourcellsobservedattheinvasivefrontofcolorectal

adenocarcinomasarecharacterisedbyanenhancedcapabilityto

migrateandinvade.

31

Aneuploidyhaslongbeenknowntobeassociatedwithan

increasedexpressionofgenesrelatedtoEMT,cancercellmigration,

invasionandmetastasis.

32

However,differentaneuploidieshave

distincteffectsoncancercellinvasion.

33

Forexample,DLD-1

colorectalcancercellswithtrisomyofchromosome7or13invade

moreactivelythandiploidcells,bothinstandardandstressful

conditions(hypoxia,etc.)invitro.

34

Similarly,trisomyofchromosome

5enhancestheinvasivepotentialofHCT116colorectalcancercells

invitroandinvivothroughpartialEMTandupregulationofmatrix

metalloproteinases(MMPs).

33

Bycontrast,trisomyofchromosome

13or18signi?cantlydecreasesinvasionofHCT116colorectalcancer

cellsinvitro,potentiallybecauseofaneuploidy-induceddosage

imbalancesthatmayinterferewithdifferentcellularfunctions,

includingcellmotility.

33

StructuralCIN

Chromosomalrearrangementscanleadtothelossoftumoursuppressorsand/ortheampli?cationofoncogenesandcancontributetocancerprogression.

Genefusionsareafrequentresultofchromosomalrearrange-

mentsandcanresultfromtranslocations,deletions,inversions

andduplications,aswellaschromothripsis,acatastrophic

genomiceventleadingtomassiverearrangementsofmultiple

chromosomes.

35

Owingtothelargenumberofgenefusions,their

roleincancercellmigrationandinvasioncouldbethetopicof

anotherreview,soweconsiderheresomeofthemostcommon

genefusions.The?rstgenefusiontobediscovered,BCR-ABL,is

theresultofareciprocaltranslocationbetweenchromosomes22

and9,andisdetectedin>96%ofpatientswithchronicmyeloid

leukaemia.

35

Thisfusioncausesalterationsintheactincytoske-

letonthatpromotethemotilityofchronicmyeloidleukaemiacells,

asdemonstratedinvariouscelllinesinvitro.

36

,

37

The

TMPRSS2-ERGgenefusioncanarisefromtheinversionor

interstitialdeletionofchromosome21q22andisfoundin50%

ofprostatecancers.

35

Thisgenefusionleadstotheoverexpression

ofERG(ETS-relatedgene),atranscriptionfactor,which,inturn,

promotesprostatetumourcellmovementthroughNotchsignal-

lingortranscriptionalactivationofMMP9andplexinA2,a

semaphorinco-receptor.

38

-

40

ERGoverexpressionasaresultofthe

TMPRSS2-ERGgenefusioneventhasbeendemonstratedto

inducingWNTsignalling.

41

,

42

Othergenefusionsalsocontribute

promoteEMTnotonlybyactivatingTGF-βsignallingbutalsoby

toEMT.TheMLL-AF9translocationt(9;11)isfoundinacute

myeloidleukaemiaandpromotestumourinvasionassociatedwith

thetranscriptionfactorZEB1inalong-termhaematopoieticstem-

cell-derivedmousemodelofacutemyeloidleukaemia.

43

Fusions

betweentheoestrogenreceptorgene(ESR1)andYAP1(which

encodesYes1-associatedtranscriptionalregulator)orPCDH11X

(whichencodesthecelladhesionproteinprotocadherin11X-

linked)areassociatedwiththeinductionofEMTandwereshown

toenhancethemotilityofT47Dbreastcancercellsinvitroandthe

metastasisofT47Dxenografts.

44

Geneampli?cationsarefrequentlyoccurringeventsinmany

cancersandresultinoverexpressionofgenes—mainlyoncogenes—

thatconferagrowthorsurvivaladvantageoncancercells.Indeed,

ErbB2geneampli?cationisoneofthemostfrequentgeneticevents

inbreastcancer,resultingintheoverexpressionofHER2,which

promotescellproliferationpredominantlythroughtheactivationof

themitogen-activatedproteinkinase(MAPK)pathway.However,

ErbB2geneampli?cationcanalsoinducebreastcancercell

migrationandinvasionthroughtheHER2-mediatedactivationof

theRhoGTPasesRac1andCdc42,masterregulatorsofcytoskeletal

dynamics.

45

,

46

Overexpressionof?broblastgrowthfactorreceptor1

(FGFR1)duetoampli?cationofthecorrespondinggeneFGFR1

promotesEMTandincreasesmigrationandinvasionofH1581

NSCLCcellsandDMS114small-celllungcancercellsinvitroby

upregulatingtheexpressionofthetranscriptionfactorSOX2,oneof

thecoreoperatorsofstemnessandEMT.

47

Theampli?cationofwild-

typeEGFRandsubsequentactivationoftheepidermalgrowthfactor

receptor(EGFR)contributetothenon-angiogenicinvasivegrowthof

glioblastomainthepatient-derivedratxenograftmodelprobably

throughtheinductionofEMTandcorrelatewithglioblastoma

invasioninpatients.

48

Ampli?cationofgrowthfactorreceptorgenesisnottheonly

waytoinducecancercellinvasionandmigration.Ampli?cationof

chromosomeregion11q13,whichencompassesgenesencoding

regulatorsoftheactincytoskeletonandcellmotility(e.g.,

cortactin,co?linandp21-activatedkinase1),occursin30-50%

ofheadandnecksquamouscellcarcinomas(HNSCC).

49

Aninvitro

studydemonstratedthat11q13ampli?cationpromotesthe

overexpressionofcortactin,whichbindstoandactivatesthe

Arp2/3actin-nucleatingcomplex,leadingtotheincreased

migrationandinvasionofvariousHNSCCcelllines(UMSCC2,

UMSCC19andMSK921).

50

Bycontrast,11q13ampli?cation-driven

overexpressionofthePPFIA1gene,whichencodesliprin-α1,a

proteinpotentiallyinvolvedincell-matrixinteractions,suppresses

migrationandinvasionofFaDuHNSCCcellsinvitro.

51

These

resultsindicatethepresenceofbothpositiveandnegative

regulatorsofcellmotilityinthischromosomalregion.Ampli?ca-

tionofanotherchromosomeregion,11q22.1-q22.2,isoftenfound

inoralsquamouscellcarcinomasandisassociatedwithlymph-

nodemetastasis.Thisampli?cationleadstooverexpressionofthe

BIRC3gene,theproteinproductofwhich—cellularinhibitorof

apoptosis(cIAP)2—enhancesthemigrationandinvasionof

SCC29Boralsquamouscarcinomacellsinvitro.

52

Additionalstudieshaveshownthatampli?cationofchromo-

someregionsharbouringnon-codingRNAsalsotriggerstumour

cellmigrationandinvasion.Gene-ampli?cation-drivenlongnon-

codingRNA(lncRNA)SNHG17promotesthemigrationofA549

andPC-9NSCLCcellsinvitro,

53

whereasampli?cationoflncRNA

PCAT6isimportantformotilityinHepG2andSMMC-7721

hepatocellularcarcinomacellsinvitro.

54

Ampli?cationand

subsequentoverexpressionofmiR-151directlytargetsRhoGDIA,

aputativemetastasissuppressor,topromotethemigrationand

invitroandthemetastasisofSMMC-7721cells.

55

MiR-182,a

invasionofHuh7andSMMC-7721hepatocellularcarcinomacells

memberofthemiRNAclusterinthechromosomallocus7q31-34

thatisfrequentlyampli?edinmelanoma,stimulatesthemigration

ofSK-MEL-19melanomacellsinvitroandincreasesthemetastatic

potentialofB16F10mousemelanomacells.

56

GENEALTERATIONS

Inadditiontoharbouringchromosomalabnormalities,differentcancersalsocontainanabundanceofpointmutationsaswellas

MutationaldriversofcancercellmigrationandinvasionNMNovikovetal.

Ce

e

c

n

a

e

m

n

o

e

n

t

e

n

i

G

a

m

r

o

t

s

c

r

a

o

f

t

p

h

t

e

w

c

e

o

r

r

G

EMT

g

n

i

l

a

y

s

e

n

e

g

r

e

h

t

O

EGFRFGFR1FGFR2

BRCA1STAG2

TP53

TRIM21TGFBR2APC

RAC1

Rassignpathwa

MAP2K4

KRAS

HRAS

NRAS

BRAF

ERK3

Cancerinvasion

g

n

i

l

a

y

n

a

g

w

i

s

h

t

K

a

3

p

I

P

PIK3CAPTEN

AKT1

mTOR

CAV1

PTPN11

CASP8

e

s

CTNNB1

C

o

G

T

P

a

s

CTNNA2PXN

FAK

RHOACDC42

e

l

l

A

a

d

R

h

PREX2RGS7

d

h

CDH1MMP8

h

e

s

i

m

o

n

ABI1ARHGAP35

e

s

i

o

n

t

r

e

o

a

r

s

e

t

ADAMTS18ADAMTS16

PAK4

o

n

a

n

d

P

r

o

t

e

o

l

a

m

r

e

U

g

p

u

s

l

a

t

t

o

s

k

e

l

ROCK1

i

s

p

r

o

t

e

y

s

e

s

t

i

n

c

y

Downstreffector

o

l

y

s

i

s

A

c

Fig.3Genealterationsandcancerinvasion.Variousgenemutationscanaffecttumourcellmigrationandinvasion.Genesresponsibleforgenomemaintenancearefrequentlymutatedincancers;however,onlyafewofthemcanin?uencetumourcellmotility,themainplayerherebeingTP53anditsdiversemutantforms.Alterationsingenesthatplayaroleincellsurvivalaffectavarietyofcellularprocessesandsignallingpathwaysunderlyingcellmigration.Mutationsingenesencodingregulatorsoftheactincytoskeleton,adhesion,proteolysisandEMTdirectlyin?uencetheabilityoftumourcellstomigrateandinvade.

geneinsertionsanddeletions(indels).Thesegenealterationsplay

asigni?cantroleinvariousstagesofcancermetastasis,and

invasionisnoexception.

57

Below,weoutlinethosegeneswhose

alterationaffectsthemigrationandinvasionoftumourcells;they

aredividedintoseveralgroups,dependingontheirprimary

function(Fig.

3

).

Genesinvolvedingenomemaintenance

Genesinvolvedinmaintaininggenomestabilityareoftenmutated

incancer.Notonlydoloss-of-function(LOF)mutationsofthese

tumoursuppressorscontributetotheacquisitionofamutator

phenotypebytumourcells,buttheycanalsoaffectcancercell

migrationandinvasion.MutationsinBRCA1leadtodysregulation

oftheUbc9/caveolin-l/vascularendothelialgrowthfactor(VEGF)/

SIRTl/oestrogenreceptor(ER)-αaxis,promoteEMTandtriggerthe

invitro.

58

,

59

TheSTAG2gene,theproteinproductofwhich

migrationofHCC1937triple-negativebreastcancercells

regulatescentromerecohesion,isoftenmutatedinvarious

cancers.MostSTAG2mutationsaretruncatingand,asshownin

theU2OSosteosarcomacellline,thelossofthisgeneleadsto

increasedEMT-associatedtumourcellmigrationinvitro,coin-

cidentwithdecreasedexpressionofE-cadherinandincreased

expressionofN-cadherin.

60

Thebestknown‘stabiliser’ofthegenomeandtumour

suppressor,however,isp53.TP53isoftenmutatedinawide

varietyoftumours,fromcarcinomasandsarcomastolymphomas

andleukaemias.

61

Lossofp53duetoLOFmutationsoftenleadsto

increasedactivityofthetranscriptionfactorsSnailandTwist1,

decreasedexpressionofE-cadherinandinductionofEMT.

62

–

64

In

addition,p53lossactivatesRhoGTPasestoincreasecellmigration,

asshowninmouseembryonic?broblastsandA375Pmelanoma

cellsinvitro.

65

,

66

However,lossofTP53mightnotalwaysbe

suf?cienttopromotetumourcellinvasionandmetastasis,as

105

showninvivoinPVTT-1hepatocellularcarcinomaxenograftsand

transgenicmouserhabdomyosarcomamodel,indicatingthat

gain-of-function(GOF)mutationsofthisgenearemorepotent

activatorsofthemetastaticcascade.

64

,

67

GOFmutationsinTP53causeanevenmoreprominenteffecton

tumourcellinvasivenessthandoLOFmutations.

68

,

69

DriverTP53

GOFmutationsoftenoccuratcodons175,248and273

61

and

endowthep53proteinwithnewabilitiestoregulatehundredsof

differentgenesincludingothertumoursuppressors.

70

The

mutantsp53R175HandR273Hhavebeenshowntobindto

andinactivatethetumoursuppressorp63toformamutant

p53–p63complex.

6

ThismutantcomplexsuppressesSplitand

Hairy-relatedprotein1(Sharp-1,ametastasissuppressor)and

ofMDA-MB-231breastcancercellsinvitroandinvivo,

71

aswellas

cyclinG2,andenhancesTGF-β-mediatedinvasionandmetastasis

acceleratesintegrinrecyclingandactivatessignallingbythe

receptortyrosinekinasesEGFRandMetviaRab-couplingprotein

(RCP)inH1299lungandMDA-MB-231breastcancercells.

72

,

73

In

thesecancers,mutantp53alsopromotesEGFRandMetsignalling

throughtheinactivationofasuppressorofinvasion,Dicer

ribonuclease,

74

andenhancesintegrinandEGFRrecyclingand

focaladhesionturnoverbymodulatingcomponentsofthe

endosomalmachinery.

75

Inactivationofp63byp53mutantscan

alsoaltertheexpressionofmiRNAsinvolvedintumourcell

migration.Forexample,mutant-p53-mediatedupregulationof

miR-155leadstotheincreasedmigrationandinvasionofZR-75-1

breastandH1299lungcancercellsinvitro,

76

anddownregulation

oftumoursuppressormicroRNAlet-7iinducedbythemutant

p53–p63complexleadstoenhancedinvasionofH1299lung

cancercellsinvitro.

77

AsdemonstratedinH1299lungcancercells

invitro,formationofthemutantp53–p63complexandthe

associatedincreaseincancercellmigrationandinvasioncanbe

inhibitedbytheactivatingtranscriptionfactor3(ATF3)protein,

whichbindsthemutantformsofp53andthusfacilitatesp63

activation.

78

,

79

Itisimportanttonotethatthemutantp53–p63

complexandthemechanismsdescribedabovearenotalways

requiredforthemigrationandinvasionoftumourcells.

InactivationofDicerribonucleasemediatedbymutantp53can

occurindependentlyoftheformationofthemutantp53–p63

complex.

74

Inaddition,GOFmutantformsofp53cantriggerEMTvia

overexpressionofTwist,

80

stabilisationofSlug

81

andalsobyacting

onZEB1.

82

Mutantp53canenhancetheexpressionoftheA1AT

protein,whichpromotesEMT-associatedmigrationandinvasion

ofH2009lungcancercellsinvitro,anddrivesinvasionofH2009

cellsinthechickchorioallantoicmembraneinvivoassay.

83

The

p53R248QmutantactivatesthephosphorylationofStat3,which

colorectalcancercellsandH1299NSCLCcellsinvitro.

84

Micewith

resultsintheenhancedEMT-dependentmigrationofHCT116

p53mutationsinadditiontothelossofanothertumour

suppressor,RB1,developmammarytumourswithEMTfeatures.

85

NumerousotherstudieshavedemonstratedtheeffectofGOF

p53mutationsonamultitudeofcelllocomotionregulators.

69

It

shouldbenoted,however,thatp53mutantscanimpactcell

movementnegativelyaswellaspositively